Engine system components (such as cylinders, valves, pistons, injectors, etc.) may be intermittently diagnosed for damage incurred during engine operation. The components may also be diagnosed to identify degraded functionality (e.g., incorrect flow, leakage, etc.).
Diagnostics may involve visually inspecting the components for scoring damage, such as by removing a spark plug and obtaining a bore scope to view inside the cylinder. In another approach, described by Yalin et al in US 2006/0037572, light from a cylinder spark event and/or combustion flame is used to diagnose for the presence of build-up and contaminants in the cylinder.
The inventors herein have recognized that the above discussed approaches can add extensive time, cost, and complexity to the diagnostics. In particular, most of the above approaches require a skilled technician, complex diagnostic tools, specialized laboratory facilities, and time consuming engine teardown. In view of these issues, the inventors have realized that in engine systems configured with laser ignition capabilities, components of the laser ignition system can be advantageously used to diagnose various engine system components. In one example, the engine may be diagnosed by a method comprising: initiating cylinder combustion by operating a laser ignition device; generating an in-cylinder image after operating the laser ignition device using light generated via the cylinder combustion; and displaying the generated image to an operator (e.g., a service technician) on a vehicle display device. The operator may then indicate degradation of a cylinder component (e.g., piston head, photodetector lens, etc.) or a cylinder combustion characteristic (e.g., flame propagation, flame initiation, etc.) based on the displayed image. In this way, engine cylinder diagnostics can be expedited and simplified without necessitating engine disassembly.
For example, the optics of the laser ignition system can be used to diagnose the cylinder during a combustion event. In particular, high power light pulses may be emitted by the laser ignition device into the cylinder (e.g., during a compression stroke) to initiate cylinder combustion. In-cylinder images may then be captured by a photodetection system coupled to the head of the cylinder using light generated from the cylinder combustion event. The photodetection system may include a camera (such as a CCD camera) and a lens (such as a fish-eye lens), for detecting the light pulses. In one example, the light pulses may be emitted in the infra-red (IR) spectrum by the laser ignition device, and detected in the IR spectrum by the camera. Images of a condition of the interior of the cylinder during the combustion may then be generated based on the detected pulses. The images may be indicative of, for example, a condition of the piston head, flame propagation pattern, flame initiation location, flame initiation pattern, timing of combustion peak pressure, etc., and may be used to infer degradation. The images may be transmitted (e.g., wirelessly) within the engine system and displayed to a service provider (e.g., mechanic or vehicle operator) on a display of a vehicle center-console. In addition, a reference image of the cylinder component/condition being diagnosed may be retrieved from the controller's memory and displayed to the mechanic for comparative analysis.
For example, when the image generated is indicative of a piston head condition, the reference image displayed may be indicative of an expected piston head condition. A discrepancy between the images may then be used to diagnose the piston head (e.g., identify piston head melting). As another example, when the image generated is indicative of a flame initiation location, the reference image displayed may be indicative of an expected location of flame initiation. A discrepancy between the images may then be used to diagnose the photodetection system's converging lens. Optionally, if the engine is coupled in a hybrid electric vehicle, an electric motor may be operated during engine operation to maintain engine speed-load conditions at a reference speed-load while the in-cylinder images are generated. If the mechanic determines that the generated image is sufficiently different from the reference image, the mechanic may determine that there is component degradation and may indicate the same to the controller via the display device. Accordingly, a diagnostic code may be set on the engine's controller.
In this way, it may be possible to take advantage of a laser ignition system to reduce the time and cost associated with the visual inspection of an engine, without reducing the accuracy of the inspection. By comparing cylinder images gathered by a photodetector following combustion in a cylinder, various cylinder components and conditions can be diagnosed. The diagnostic images generated can be displayed to a mechanic, along with reference images for comparison, so that the mechanic can identify cylinder component degradation. By using hardware already available in an engine configured with a laser ignition system, the need for costly, labor intensive, and time-consuming visual inspections can be reduced. Overall, engine inspection can be simplified without reducing inspection accuracy.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.